
// SQLite3
// -------
var _              = require('lodash')
var Promise        = require('../../promise')

var inherits       = require('inherits')
var assign         = require('lodash/object/assign')
var pluck          = require('lodash/collection/pluck');

var Client         = require('../../client')
var helpers        = require('../../helpers')

var QueryCompiler  = require('./query/compiler')
var SchemaCompiler = require('./schema/compiler')
var ColumnCompiler = require('./schema/columncompiler')
var TableCompiler  = require('./schema/tablecompiler')
var SQLite3_DDL    = require('./schema/ddl')

function Client_SQLite3(config) {
  Client.call(this, config)
  if (_.isUndefined(config.useNullAsDefault)) {
    helpers.warn('sqlite does not support inserting default values. Set the `useNullAsDefault` flag to hide this warning. (see docs http://knexjs.org/#Builder-insert).');
  }
}
inherits(Client_SQLite3, Client)

assign(Client_SQLite3.prototype, {

  dialect: 'sqlite3',

  driverName: 'sqlite3',

  _driver: function() {
    return require('sqlite3')
  },

  SchemaCompiler: SchemaCompiler,

  QueryCompiler: QueryCompiler,

  ColumnCompiler: ColumnCompiler,

  TableCompiler: TableCompiler,

  ddl: function(compiler, pragma, connection) {
    return new SQLite3_DDL(this, compiler, pragma, connection)
  },

  // Get a raw connection from the database, returning a promise with the connection object.
  acquireRawConnection: function() {
    var client = this;
    return new Promise(function(resolve, reject) {
      var db = new client.driver.Database(client.connectionSettings.filename, function(err) {
        if (err) return reject(err)
        resolve(db)
      })
    })
  },

  // Used to explicitly close a connection, called internally by the pool
  // when a connection times out or the pool is shutdown.
  destroyRawConnection: function(connection, cb) {
    connection.close()
    cb()
  },

  // Runs the query on the specified connection, providing the bindings and any other necessary prep work.
  _query: function(connection, obj) {
    var method = obj.method;
    var callMethod;
    switch (method) {
      case 'insert':
      case 'update':
      case 'counter':
      case 'del':
        callMethod = 'run';
        break;
      default:
        callMethod = 'all';
    }
    return new Promise(function(resolver, rejecter) {
      if (!connection || !connection[callMethod]) {
        return rejecter(new Error('Error calling ' + callMethod + ' on connection.'))
      }
      connection[callMethod](obj.sql, obj.bindings, function(err, response) {
        if (err) return rejecter(err)
        obj.response = response;

        // We need the context here, as it contains
        // the "this.lastID" or "this.changes"
        obj.context  = this;
        return resolver(obj)
      })
    })
  },

  _stream: function(connection, sql, stream) {
    var client = this;
    return new Promise(function(resolver, rejecter) {
      stream.on('error', rejecter)
      stream.on('end', resolver)
      return client._query(connection, sql).then(function(obj) {
        return obj.response
      }).map(function(row) {
        stream.write(row)
      }).catch(function(err) {
        stream.emit('error', err)
      }).then(function() {
        stream.end()
      })
    })
  },

  prepBindings: function(bindings) {
    return _.map(bindings, function(binding) {
      if (binding === undefined && this.valueForUndefined !== null) {
        throw new TypeError("`sqlite` does not support inserting default values. Specify values explicitly or use the `useNullAsDefault` config flag. (see docs http://knexjs.org/#Builder-insert).");
      } else {
        return binding
      }
    }, this);
  },

  // Ensures the response is returned in the same format as other clients.
  processResponse: function(obj, runner) {
    var ctx      = obj.context;
    var response = obj.response;
    if (obj.output) return obj.output.call(runner, response)
    switch (obj.method) {
      case 'select':
      case 'pluck':
      case 'first':
        response = helpers.skim(response)
        if (obj.method === 'pluck') response = pluck(response, obj.pluck)
        return obj.method === 'first' ? response[0] : response;
      case 'insert':
        return [ctx.lastID];
      case 'del':
      case 'update':
      case 'counter':
        return ctx.changes;
      default:
        return response;
    }
  },

  poolDefaults: function(config) {
    return assign(Client.prototype.poolDefaults.call(this, config), {
      min: 1,
      max: 1
    })
  }

})

module.exports = Client_SQLite3
